Sorry, I'm not following. I want my blog to be in a topic. You know when you look up new blogs by searching through different topics? Does that happen automatically if I categories my posts? I'm totally lost

There is only one dynamic page for posts in any blog. By default that is the front page of the blog. Thus, the accurate answer to your question is "you can't post to more than one page on a blog".

Pages http://en.support.wordpress.com/pages/ that we bloggers create are static ie. they do not automatically update with new content. Only dynamic pages which are automatically created by the software when we publish a post ie. categories, tags, archives pages will update.

There is only one dynamic page for posts that automatically updates in a blog and all posts will display on that page. There is no way to exclude posts from the main posts (blog) page. By default the front page of the blog will display your posts (not pages) in reverse chronological order, with the most recently published post on top. If you do not want all the posts to show on the front page, then you can create a static front page http://en.support.wordpress.com/pages/front-page/